The domestication of many plants has correlated with dramatic increases in yield. Most phenotypic variation occurring in natural populations is continuous and is effected by multiple gene influences. The identification of specific genes responsible for the dramatic differences in yield, in domesticated plants, has become an important focus of agricultural research.
In Arabidopsis, one family of genes associated with plant changes that relate to improved yield in crops, the (ARGOS) Auxin-Regulated Gene involved in Organ Size gene is inducible by auxin. This gene is responsible for the regulation of cell proliferation and organ growth. The Arabidopsis ARGOS is naturally expressed at a low level in various young tissues including roots, inflorescence stems, flower, young rosette leaves and silliques, but undetectable in mature leaves. In studies by Hu, et al., (2003 Plant Cell 15:1951-61) and Hu, et al., (2006 The Plant Journal 47(1):1-9), transgenic plants that ectopically over-express sense or antisense ARGOS cDNA display enlarged or reduced aerial organs, respectively. Alteration in organ size demonstrate in these plants is associated with changes in cell number, and not cell size. The increased cell number is attributed to the duration of organ growth in Arabidopsis. 
The present invention includes the identification of the putative maize ARGOS genes, ZmARGOS 1-9 (SEQ ID NOS: 1, 3, 5, 40-45 and 71) that are related to the Arabidopsis ARGOS genes (SEQ ID NOS: 59, 60 and 61). The ortholog having the most similarity to Arabidopsis ARGOS (SEQ ID NO: 59), is ZmARGOS 1 (SEQ ID NO: 1). ZmARGOS 1 and 2 (SEQ ID NOS: 1 and 3) expression in maize was primarily in the roots, early endosperm, immature ear and shoot and ear inflorescent meristems. The expression is associated with actively growing tissues, and is found to a lesser degree in the mature tissues. This finding is consistent with the noted positive effect of the gene on regulating growth and cell proliferation. The ZmARGOS 3 gene (SEQ ID NO: 5) expressed in a wide spectrum of tissues and developmental stages.
Transgenic plants expressing ZmARGOS 1 (SEQ ID NO: 1) show a positive impact on biomass accumulation and rate of maize plant growth, as well as an increase in organ size. These maize genes will find utility for enhancing agronomic traits in maize (and other crops).
The present invention also includes the identification of ARGOS genes in other plant species. The rice gene family is represented by 8 family members. Nine members of the gene family were found in Sorghum bicolor. Five gene sequences were also found in Soybean (Glycine max). Three members of the ARGOS Arabidopsis gene family are disclosed herein.